U.S. Pat. No. 5,091,124 (Zakich) discloses a high tonnage reaction injection molding (RIM) press has fixed and movable platens for clamping a composite mold therebetween at a closed mold position. A plurality of high pressure hydraulic cylinders are mounted on a carrier for the movable platen, and a locking mechanism having a plurality of incrementally spaced locking positions is effective to lock the carrier selectively at said positions. A pair of low power hydraulic piston-cylinder assemblies connected with the carrier adjacent to its opposite ends move the carrier and movable platen to the closed position. Short stroke connecting rods operated by the high pressure cylinders are forced independently of each other into high tonnage engagement with the movable platen at a plurality of locations within the area of the composite mold to clamp the latter between the platens and positively seal its junctions, whereupon a RIM mix head injects the high pressure reactive chemicals into the sealed mold.
U.S. Pat. No. 6,733,275 (Mitsubishi) discloses an electric split nut opening/closing device in which an electric motor is driven, and a half piece is moved linearly while the motion is restrained unequivocally, by which two left and right tie bars can be opened and closed at the same time by one device. In the electric split nut opening/closing device in which a tip-end threaded portion 65a of a tie bar 65, one end of which is fixed to either one of a fixed platen 61 and a movable platen 62 and the other end of which is projected by penetrating the other platen, is engaged with split nut 71, 72 provided on the other platen to connect the fixed platen 61 to the movable platen 62, by which a mold clamping force is generated between the platens by giving tension to the tie bar 65, a pair of left half piece 71a, 72a and right half piece 71b, 72b of the split nut 71, 72 are slidably supported so as to hold the tie bar 65 therebetween, and the left half piece 71a, 72a and right half piece 71b, 72b of the two sets of split nuts 71 and 72 are brought into contact with and separated from each other at the same time by common driving means 86 so as to hold the tie bar 65.
U.S. Pat. No. 7,993,129 (Chen Hsong) discloses an injection molding machine includes a lock nut open-close mechanism provided on a moveable platen (1) to engage with at least two tie bars (3), and comprises a pair of rods (23, 24) connecting two pairs of lock nuts (21, 22), and a clamping unit (2). The clamping unit comprises an execution element (25) and a pair of connecting bars for open-close action (26, 27) symmetrically arranged. A first end of a first connecting bar (26) is connected to the second nut (212) of the first pair of lock nuts (21), and a first end of the second connecting bar (27) is connected to the first nut (221) of the second pair of lock nuts (22). The second ends of the first and second connecting bars are connected to each other and are driven by the execution element (25) simultaneously to open or close the pairs of lock nuts simultaneously.